Donald Trump Is Behaving 'Like an 11-year-old' by Name-calling, Says London Mayor

President Donald Trump's war of words with London Mayor Sadiq Khan is rumbling on as the commander-in-chief continues his state visit to the U.K., the majority of which is being spent in the city Khan is responsible for.

The long-held animosity between the pair erupted anew on Monday even before Trump touched down at London Stansted Airport, as the president launched his latest Twitter tirade against the progressive mayor.

Trump branded Khan a "stone-cold loser" who "by all accounts has done a terrible job as Mayor of London." He was responding to Khan's suggestion that Trump is not worthy of a state visit and that the president is not even in the same class as his predecessors Barack Obama and George W. Bush.

Speaking with BBC News on Tuesday, Khan dismissed the most recent attacks from the president and said his problem was with Trump rather than with the U.S.

Khan told the interviewer that he was not immediately aware of Trump's tweets because he was working, though said that when he found out he first thought it was a joke. Regardless, the mayor suggested that "name-calling" should be beneath any world leader, and expressed surprise that Trump would "behave like an 11-year-old."

Though Khan stressed it remains "very important we have good relations with the U.S.," he restated his objection to Trump's state visit. The mayor accused Trump of breaking with long-shared U.K.-U.S. liberal values, for example by "walking away from the Paris climate change agreement, rolling back progress on LGBT+ rights, and rolling back the reproductive rights of women."

"We've always had in common religious freedom, we've always had in common equality," Khan continued. "And in this of all weeks, when we commemorate the D-Day landings... we should be remembering these hard-fought rights."

"I do worry that you've got the leader of American who is seen as a poster-boy for far-right movements across the globe," he added. "Far-right extreme views are being normalized because they are being given succor by Donald Trump."

"If he wants to have a discussion—and I'd welcome a discussion—about some of the issues we disagree about, we should do so," Khan said.

Trump is spending much of the day with Theresa May, who will be stepping down as leader of the Conservative Party on Friday and will be replaced as prime minister soon after.

Khan told the BBC he believes it is "important for our prime express to him her concerns in relation to some of the things that he's said and done, that are the complete opposite of what we have always had in common."

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Mayor of London Sadiq Khan speaks at the annual British Chambers of Commerce conference on March 28, 2019 in London, U.K. Getty/Jack Taylor